Since the "robot voice" is the most controversial part of the Cube & Star world thus far; and since I wanted to keep the characters gender-neutral (ruling out single-source voice actors) - I had a thought:

How would you - the denizens of Steam, like to be the voice of the Cubes and Stars?

What I'm thinking is this: I will provide the script for the video - and if you're super-excited, you can record yourself (either as audio or a video reply to the trailer) - and I will subsequently mix all of your lovely voices together into an ebbing/flowing cocktail of different ages, genders and accents!

And taking that further - your name will be forever immortalized either in a credit list or... or... or...
In the pool of names from which the game character's names are drawn.

Very creative solution! Though, I have a feeling trying to make a cohesive-sounding singular voice from a multitude of different sources might prove to be very difficult. Perhaps keep each character's voice down to 2 voice actors per synthesis, one female and one male mixed together for each?